1. Field of the Invention
The present invention relates to a closing element for rooms, such as, buildings, containers, superstructures of vehicles or the like. The closing element covers a two-dimensional area and can be rolled up. The closing element is of a flexible material which can be rolled up and which is reinforced transversely of its rolling direction by means of bending-resistant reinforcement layers which increase the transverse stiffness and which are embedded on both sides of a core zone within the closing element.
2. Description of the Related Art
Rolling doors whose hanging portions are composed of individual lamella-type sections of metal or plastics material which are connected to each other by means of hinges transversely of the rolling direction have been known for decades. Rolling doors of this type can be moved only slowly because they have mechanical hinges and produce unwanted, sometimes shrieking noises when they are moved. These rolling doors are susceptible to damage during everyday operation, particularly due to impacts from vehicles, such as, stacker trucks. The repair of the damage is complicated because deformed pans, such as, steel lamellas, are difficult to replace. Also, such rolling doors do not provide protection against cold temperatures and sound.
Also known in the art are so-called high-speed doors which are composed of a relatively thin flexible hanging material made from webs of textile or plastics material. These doors can be moved several times faster. In addition, they are tight against wind. However, the major disadvantage of these high-speed doors is the necessary complicated mechanism because the highly flexible materials used in the doors are not capable of transmitting thrust or pushing forces. The use of these doors is limited because they do not provide sufficient protection against break-ins and because of their manufacturing costs. As a rule, these doors can only be used within plants, and the use of the doors is essentially limited to protective curtains or auxiliary doors.
The proposal according to EP-A-0210364 was intended to eliminate the disadvantages of the above-described doors. The rolling door construction according to this reference combines a highly flexible curtain with metal or steel sections. However, this rolling door still has the significant disadvantages described above. Moreover, when hard and soft materials are connected, stresses within the hanging portion cannot be excluded, so that a satisfactory, problem-free operation duration cannot be expected, especially since too many parts are joined together and connected and must be wound up with portions rubbing against each other. This inevitably results in high manufacturing and maintenance costs.
DE-Gbm 74 32 191 discloses an improvement of a rolling door for steam chambers. This rolling door is composed of a rubber plate which is reinforced with only two fabric inserts which extend parallel to each other and are spaced apart from each other by an elastic core which can be rolled up in rolling direction. The principle of the beam used in this case did not meet expectations in spite of the thickness of the plate of up to 20 mm. because the apparent danger of decay due to the steam did not permit use of metal fabric in the outer areas of the hanging portion.
Therefore, because of the unwanted formation of waves in the hanging portion due to the absorption of water by the fabrics and the uncontrollable shrinkage behavior thereof, the elastic rubber core is stiffened between the fabrics by means of spaced-apart steel strips having a thickness of 1-2 mm. which are vulcanized into the rubber core and extend centrally transversely of the travel direction of the rolling door. The purpose of the steel strips is to prevent distortion and shrinkage of the fabric. On the other hand, the steel strips also prevent the elastic spacer core between the fabrics from being deformed transversely of the rolling axis when the steam pressure acts on the surface area of the hanging portion and from being displaced relative to the fabric layers which are arranged on both sides and act as an upper portion and a lower portion.
The rolling door according to DE-C-3531633 also utilizes the carrier principle with a soft core with reinforcements arranged on both sides for another special task, namely, as a rolling hanging portion or door of sandblast cabins. Sandblast cabins are frequently formed by adjustable rolling brackets, i.e., rolling adjustable walls. Stationary cabins with entrances require only doors which, although they have a relatively small width, can still be considered doors.
DE-C-3531633 mentions the rolling bracket with a shaft mounted thereon in the description of the drawing and also mentions "the free hanging in the manner of a curtain." Free hanging of the door and a still sufficient resistance to sandblast pressure or air pressure requires that the door has a substantial own weight and that the curtain or closing element is resistant to operation.
The resistance to abrasion and the required service life in view of the aggressive materials acting on door are obtained in practice by means of so-called wearing mixtures which have a high capability of expansion of approximately 450-600% and a low resistance to expansion.
The own weight of the curtain results from mass and is obtained by the strong outer skin for deflecting the sand blast material as well as a spacer core with two steel cord fabric layers and a fabric in the middle, wherein the spacer core is thick for this type of application and, therefore, has good damping properties. The use of fabrics in the core zones can only be considered an advantage because they neutralize the high capability of expansion of such soft mixtures and the low resistance to expansion of the particularly soft rubber material under the high weights occurring during rolling. Such an element when used as a curtain tensions itself and, as a rule, is only used within plants in order to prevent escape of sand into the surrounding area. Such closing elements cannot be used, for example, as industrial doors because they do not meet the technical requirements and are not competitive relative to other door systems as far as costs are concerned.
Because of the unfavorable expansion and upsetting behavior of the soft material in the core zone, the upper portion and lower portion are displaced relative to each other and break out toward one side. They can also not handle any pushing forces because they are too soft in rolling direction. Since a freely hanging curtain requires weight, the hanging door does not operate properly when the weight is too small. In addition, the operation of a freely hanging curtain cannot be transferred to an industrial door. A wind-tight door of a building which is guided at the edges and in the outer regions thereof must be capable of absorbing the same wind pressure as is required for a building wall. A closing member for a sand blast cabin according to DE-C-3531633 would be pressed out of the guide means at the edges already at an average wind load acting over the full width of approximately 2 meters. This is because the closing member does not have sufficient transverse stiffening means.
Finally, an economically acceptable manufacture was in the past not possible because of the requirement that conventional giant presses costing millions had to be used. At present, the width of such presses is limited to approximately 3 meters. On the other hand, the use of such presses for manufacturing closing elements of the type discussed above is not possible because of the high costs of use and amortization.